Telephone system.



No. 766,223. PATENTED AUG. 2, 1904.

W. M. DAVIS.

TELEPHONE SYSTEM.

.APPLIOATION FILED MAR. 9. 190a.

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No. 766,223. Patented August 2, 1904.

UNITED STATES PATENT OFFICE.

IVILLIAM M. DAVIS, OF CHICAGO, ILLINOIS, ASSIGNOR TO S'lTROhIBERG- CARLSON TELEPHONE MANUFACTURING COMPANY, OF ROCHESTER, NEIV YORK, A CORPORATION OF NEWV YORK.

TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 766,223, dated August 2, 1904.

Application filed March 9, 1903. Serial No. 146,918. (No model.)

"17mm 7715 y 0070087711: winding, receives directly a portion of the Beitknown that I, l/VILLIAH M. DAVIS, aciticurrent flowing in the circuit, and in addition 5 zen of the United States, residing at Chicago, it receives the currents induced upon the secin the county of Cook and State of Illinois, ondary winding by the primary winding, the

have invented a certain new and useful Imtwo currents cooperating in their effect upon provement in Telephone Systems, of which the the receiver. following is a full, clear, concise, and exact de- I shall describe my invention more clearly 5 5 scription, reference being had to the accomby referring to the accompanying drawings, panyingdrawings,formingapart of this speciin which in Figure 1 I have shown the appli- IO tication. cation of the invention to a common-battery My invention relates to telephone systems, system and have shown two subscribers conand has for its object improved disposition of nected together for conversation by means of 60 apparatus and connections whereby telephonic central cord mechanism and circuits, and in currents are greatly increased in strength and Fig. 2 .I have shown diagrammaticall y the po- I 5 transmission of voice-currents improved. sition and arrangement of circuits in accord- I will describe my invention as used in conance with my invention, like characters of refnection with substation apparatus, although erence referring to like parts throughout the 5 its use is not limited to that arrangement of figures. apparatus, andIemploy substation apparatus, The substation apparatus consists of a rewhich may consist of a receiver, atransmitter, ceiver 1, a transmitter 52, a primary winding primary and secondary windings, and suitable 23, secondary winding 4., a switch-hook 5, and switching mechanism. I preferably include a signal 6, the signal being included in circuit 7 the primary and the secondarywindings seriwith a condenser connected across the line ally in circuit with the transmitter, the transwhen the receiver is on the hook. The primitter being preferably connected between mary winding 3, the transmitter 2, and the the primary and the secondary windings. The secondary winding @L when the subscriber rereceiver-circuit preferably forms a shunt moves the receiverfromthehook are included 75 about the secondary winding. The primary serially in circuit with the limbs 11 7), extendand secondary windings are also preferably ing between the subscribers, the transmitter of substantially equal resistance, and to this being connected between the primary and the end I may advantageously employ a coil, such secondary windings. A common battery 7 in as is described in my Patent No. 715,999, iscircuit with impedance 8 may be connected 3O sued December 16, 1902. The fact that the across the limbs 11 and b. The circuit, includprimary and secondary windings are of subing the receiver 1, forms a shunt 0 about the 3 5 stantially equal resistance in itself tends to secondary windings. \VindingsSandimay be strengthen the telephonic currents, for the made of substantially the same resistance, and reason that the impedance in the primary cirthe coil containing the windings may be such cuit is counteracted by the effect of the secas is described in my patent hereinbefore reondary circuit. However, by arranging the ferred to, the object of this substantially equal 4 apparatus and connections as above described resistance in the windings being to destroy I find that I can still further increase the the impedance to the talking-currents in a strength of the talking-currents in the remanner as described in the patent referred to. 9 ceiver, the apparent cause for this being the In addition to thus strengthening the talkinginducing effect of the primary winding upon currentsI find that by the useof my improved the secondary winding. The talking-currents connections they are still further increased in pass serially through the primary and secondstrength, apparently caused by the inducing ary windings, and the receiver, which is coneffect of the primary winding upon the secnected in a shunt-circuit around the secondary ondary winding.

When the subscribers are in talking relation, as shown, voicecurrents initiated at substation a: are received at station y through limb a, secondary winding 4:, transmitter 2, primary winding 3, and back through limb b. The receiver, which is included in the shunt 0, receives directly a portion of the currents flowing through the circuit just traced, and in addition it receives the currents induced upon the secondary winding by the primary winding, the direct and the induced currents cooperating in their eflect upon the receiver. The talking-circuit between the substations may include at the exchange a suitable cord-circuit (Z, the common battery 7, and the impedance 8. My invention may also advantageously be applied to the operators circuit a, associated with the cord-circuit.

I do not wish to have my invention limited to uses as herein referred to, as it may be employed wherever the cooperative effect of di rect and induced currents would be of advantage; but,

, Having thus described my invention, I claim as new and desire to secure by Letters Patent 1. In a telephone system, the combination with the primary and secondary windings of an induction-coil included only serially between the limbs of a telephonic circuit, of a battery and a transmitter included in said circuit, and a receiver included in a shunt circuit about said secondary winding whereby to receive directly a portion of the current flowing in said circuit and to receive in addition the currents induced upon the secondary winding by the primary winding, substantially as described.

2. In a telephone system, the combination with the primary and secondary windings of an induction-coil, said windings being included only serially between the limbs of a telephonic circuit, of a battery anda transmitter included in said circuit, said secondary winding having substantially the same resistance as the primary winding whereby to counteract impedance in said circuit, and a receiver included in a shunt-circuit about said secondary winding whereby to receive directly a portion of the current flowing in said circuit and to receive in addition the currents induced upon the secondary winding by the primary winding, substantially as described.

3. In a telephone system, the combination with subscribers substations, of a circuit for connecting subscribers for conversation, means at one of said substations for initiating voice-currents in said circuit, an inductioncoil at another station having its primary and secondary windings included only serially in said circuit, and a receiver connected in parallel with said secondary Winding whereby to receive directly a portion of the voice-currents fiowingin said circuit and to receive 4. In a telephone system, the combination with subscribers substations, of a circuit for connecting subscribers for conversation, means at one of said substations for initiating voicecurrents in said circuit, an inductioncoil at another station having its primary and secondary windings included only serially in said circuit, and a receiver connected in parallel with said secondary winding whereby to receive directly a portion of the voice-currents flowing in said circuit and to receive said currents inductively, the primary and secondary windings of said induction-coil being of substantially equal resistance whereby the impedance in said circuit is counteracted, substantially as described.

5. In a telephone system, the combination with a battery and a transmitter included in a telephonic circuit, of the windings of an induction-coil included only serially in said circuit, and a receiver connected in a shunt-circuit about one winding of said coil, said shuntcircuit including only said receiver, substantially as described.

6. In a telephone system, the combination with a battery and a transmitter included in a telephonic circuit, of the windings of an induction-coil included only serially in said circuit, and a receiver connected in a shunt-circuit about one winding of said coil, said shuntcircuit including only said receiver, the windings of said induction-coil having substantially the same resistance whereby to counteract the impedance in said telephonic circuit, substantially as described.

7. In a telephone system, the combination with the primary and secondary windings of an induction-coil included only serially in a telephonic circuit, of a battery and a transmitter included in said circuit, and a receiver included in a shunt-circuit about said secondary winding, said shunt-circuit including said acted, and a receiver included in a shunt-circuit about said secondary winding, said shuntcircuit including said receiver only, substantially as described.

9. The combination with atelephone-circuit including only serially and in the order named, a battery, a primary winding of an inductioncoil, a transmitter, and a secondary winding of an induction-coil, of a receiver connected in a shunt-circuit about said secondary winding, substantially as described.

10. The combination with a telephone-circuit including only serially and in the order named, a battery, a primary winding of an induction-coil, a transmitter, and a secondary winding of an induction-coil, of a receiver connected in a shunt-circuit about said secondary winding, said shunt-circuit including said receiver only, substantially as described.

11. The combination with a telephone-circuit including only serially and in the order named, a battery, a primary winding of an induction-coil, a transmitter, and a secondary winding of an induction-coil, of a receiver connected in a shunt-circuit about said secondary winding, the resistances of said primary and secondary windings being substantially equal whereby impedance in said telephone-circuit is counteracted, substantially as described.

12. The combination with a telephone-circuit including only serially and in the order named, a battery, a primary winding of an induction-coil, a transmitter, and a secondary winding of an induction-coil, of a receiver connected in a shunt-circuit about said secondary winding, the resistances of said primary and secondary windings being substantially equal whereby impedance in said telephone-circuit is counteracted, said shunt-circuit including With two line-limbs connected together at a substation only serially through the windings of an induction-coil, of a transmitter included serially in circuit with the windings, and a receiver bridging one of said windings.

In witness whereof I hereunto subscribe my name this 6th day of hlarch, A. .l). 1903.

WILLIAM M. DAVIS.

Vitnesses:

HARVEY L. HANSON, CHARLES J. SCHMIDT. 

